Mobile unit navigation system and mobile unit navigation method

1. A mobile unit navigation system comprising: a position detector for detecting the current position of a mobile unit; a map information acquisition unit for acquiring map information from a storage medium or an external system; an input unit for specifying a destination; a route search unit for searching for a guide route from the current position to the destination based on the map information; and an output unit for displaying the found guide route as an image or guiding a user along the found guide route with voice; wherein said route search unit comprises a move route extraction unit for extracting a move route of the mobile unit based on a move path of the mobile unit provided by said position detection unit and the map information, a differential route registration unit for extracting a differential route which reflects a difference between the guide route and the extracted move route and registering the differential route, and a differential route application unit for applying the registered differential route to searching for the guide route.

2. The mobile unit navigation system as claimed in claim 1 wherein said move route extraction unit comprises a correction unit, if the extracted move route contains a discontinuous part, for correcting the move route to a continuous move route by complementing the discontinuous part based on the peripheral map information.

3. The mobile unit navigation system as claimed in claim 1 wherein the differential route is a continuous link chain.

4. The mobile unit navigation system as claimed in claim 1 wherein said differential route application unit replaces a part of the guide route with the differential route.

5. The mobile unit navigation system as claimed in claim 4 wherein if the start point and the end point of the differential route are contained on the guide route, said differential route application unit replaces the corresponding portion of the guide route from the start point to the endpoint with the differential route.

6. The mobile unit navigation system as claimed in claim 1 wherein said differential route registration unit registers each differential route to which additional information indicating the attribute and history of the differential route is added.

7. The mobile unit navigation system as claimed in claim 6 wherein the additional information contains any of the following or any combination thereof: 1) Registration date and time of differential route; 2) move date and time of mobile unit on differential route; 3) number of times mobile unit has been moved on differential route; 4) move direction of mobile unit on differential route; 5) required time for mobile unit to pass through differential route; 6) passage speed of mobile unit on differential route; 7) position and direction of differential route; 8) route length of differential route; 9) road width of differential route; 10) number of lanes of differential route; 11) inclination degree of differential route; 12) pavement percentage of differential route; 13) open date of differential route; 14) toll required for differential route; 15) limited speed on differential route; 16) limited height on differential route; 17) limited weight on differential route; 18) traffic control on differential route (number of lanes, travel in one direction only, chain, etc.) and period and times of traffic control; 19) duplication degree with other differential routes 20) number of times differential route has been applied to guide route.

8. The mobile unit navigation system as claimed in claim 6 wherein said differential route application unit comprises a priority determination unit for determining priority of each differential route based on the additional information and applies the differential route to searching for a guide route based on the determined priority.

9. The mobile unit navigation system as claimed in claim 8 wherein said differential route application unit comprises a differential route deletion unit for deleting an unnecessary differential route based on the priority thereof.

10. The mobile unit navigation system as claimed in claim 8 wherein said differential route application unit comprises an application determination unit for determining whether or not application of a differential route to a guide route is required and an application determination unit determines whether or not application of the differential route to the guide route is required based on the priority of the differential route.

11. The mobile unit navigation system as claimed in claim 6 wherein said input unit comprises a discriminate information input unit for adding discriminate information to additional information to each differential route registered by said differential route registration unit.

12. The mobile unit navigation system as claimed in claim 11 wherein the discriminate information contains the identification name or identification number of each differential route or information indicating whether or not application of each differential route to a guide route is required.

13. The mobile unit navigation system as claimed in claim 1 wherein said differential route application unit comprises an application determination unit for determining whether or not application of a differential route to a guide route is required.

14. The mobile unit navigation system as claimed in claim 13 wherein said application determination unit determines whether or not application of a differential route to a guide route is required based on the positional relationship between the current position of the mobile unit and the destination.

15. The mobile unit navigation system as claimed in claim 13 further comprising a road traffic information acquisition unit for acquiring road traffic information from an external system, wherein said application determination unit determines whether or not application of a differential route to a guide route is required based on the road traffic information concerning the differential route.

16. The mobile unit navigation system as claimed in claim 13 wherein said input means comprises an application condition input unit entering an application condition of a differential route to a guide route and wherein said application determination unit determines whether or not application of the differential route to the guide route is required based on the entered application condition.

17. The mobile unit navigation system as claimed in claim 1 wherein said output means comprises a discriminate output unit for discriminately displaying each differential route registered by the differential route registration means or each differential route applied to a guide route as an image or guiding the use along the discriminated differential route with voice.

18. The mobile unit navigation system as claimed in claim 17 wherein when the current position of the mobile unit exists in the proximity of an entry point into the differential route applied to the guide route or in the proximity on the differential route, said discriminate output unit discriminately displays the differential route as an image or guiding the use along the discriminated differential route with voice.

19. A mobile unit navigation method comprising the steps of: detecting the current position of a mobile unit; acquiring map information from a storage medium or an external system; specifying a destination; searching for a guide route from the current position to the destination based on the map information; and displaying the found guide route or guiding a user along the found guide route with voice; wherein said route search step comprises the steps of: extracting a move route of the mobile unit based on a move path of the mobile unit provided by said position detection step and the map information; extracting a differential route which reflects a difference between the guide route and the extracted move route and registering the differential route; and applying the registered differential route to searching for the guide route.